Installing a salt-neutralizing flush kit can keep corrosion at bay in your high-performance engine.

By Brett Becker

It's no secret that flushing your engine after a day spent thrashing about on the open ocean is a good idea, if not mandatory. Believe it or not, several shops we've spoken with over the years say some boaters still don't always perform this essential preventive maintenance each time they use their boat in saltwater.

However, even if you flush your engines with the religious fervor of Jimmy Swaggart, you can still end up with corrosive saltwater languishing in your engine between outings. How? We asked Alan Landry, owner of Pacific Marine Repair in Ventura, Calif.

"If we ran around in saltwater, and then flush it, then the following day took some of the water out of the manifold, it's going to be salty because the metals are so porous that the salt gets in there," he said. "In flushing, you're not going to get the same expansion you get at 3,500 rpm under load out on the ocean. The block is going to be much warmer. The expansion rate is going to be much greater."

In other words, flush all you want. You will get most of the salt out of your engines' cooling systems, but not all of it. And that's not good. You can use a salt neutralizer such as Salt-Away, but getting the solution into the engine, through the drive pickup, can be imprecise. A better idea is to install an engine-flushing system on your boat. It takes a bit of work to install one, but they can save a lot of time later in terms of proper flushing and corrosion-related repairs.

"The best thing to do there—and it works because we've been watching it for a few years—is the Salt-Away-style system, an injection-style Salt-Away that goes in there and neutralizes the effects of saltwater in the block."

MerCruiser doesn't offer such a system in kit form, but you can get a kit from Volvo Penta (Part No. 3808823), and it can be installed on virtually any inboard and stern-drive engine that has a suction-type sea pump, usually driven by a belt on the engine. Unfortunately, the system won't work on boats with Alpha drives because they have push-style impellers located in the stern drive's lower gear-case housing.

Steve Fleming, director of communications for Mercury Marine, said the best method for eliminating salt from an engine is still by flushing it with freshwater. He added that MerCruiser's flush ports wash out the engine and drive, and that closed-cooling systems, which are available on virtually everything MerCruiser makes, will keep all salt out of the engine and drive components. Older engines, by and large, are still raw-water cooled.

Volvo Penta's kit, called Neutra-Salt, consists of a reservoir and a quart of salt-neutralizing solution, hoses, clamps and two connectors to tap into the raw waterline, a poppet valve, wiring and switches and some other hardware. The kit retails for about $230.

To install the system, Landry suggests mounting the reservoir high on a bulkhead, where gravity will help feed the solution into the raw-water-feed hose before the sea pump. Cut the raw-water-feed hose and install the kit's connector, which features a T-port through which the neutralizing solution will flow. Then wire the poppet valve beneath the reservoir to a power source and a dash-mounted switch and you're good to go. Or if electricity baffles you as it does many do-it-yourselfers, just have a shop install the kit.

Although Volvo Penta's literature suggests you can use the kit to flush "your engine while the boat is sitting in the water—there is no need to trailer your boat or hook up to a freshwater supply," Landry suggests otherwise.

"I recommend flushing the engine first, getting most of the saltwater out, then during the last 60 seconds of your flush, you hold the button down and allow the solution to circulate, and shut it off," he said, emphasizing that switching the ignition off first is critical. "That allows the solution to sit in the block and manifolds and risers and neutralize the effects of the existing water in the system.

"Obviously, the best time to flush an engine is when it's warm because the expansion of the metal," he continued. "All those casting flaws and everything else is open. So when you're flushing it, when the block and manifolds are warm, it flushes much better than when it's cold."

As your engine cools, saltwater that leached into the porous cast-iron surfaces within your engine will begin to weep back out as it contracts. When that happens, the solution is present in the system to neutralize the salt.

According to Volvo Penta literature, the system leaves a "corrosion-inhibiting coating on all metal surfaces, thereby neutralizing the salinity of incoming seawater."

The system is no panacea, however. Because the solution is introduced in the raw-waterline, the Neutra-Salt system will not protect drive water passages. Neutra-Salt is biodegradable, but according to the label, "Avoid excessive discharge of Neutra-Salt solution. Some local regulations may prohibit the discharge of chemicals overboard. Check for any restrictions before using."

Over time, Landry said, using a salt-neutralizing engine-flushing system will make a huge difference in the condition of water passages and junctions inside your high-performance engine. Because the water that remains in the system when the boat is not in use has been neutralized, corrosion is kept to a minimum. The flaky rust that often collects on manifold risers accumulates much slower.

"We can definitely see the differences," Landry said. "We know for a fact they work. I try to sell them all the time. It's a much more positive way to do it rather than connecting it to a flush hose at the water pickups."

Contact Information

Mercury Marine, W6250 W. Pioneer Road, Fond du Lac, WI 54936-1939, 920-929-5040, www.mercurymarine.com

Pacific Marine Repair, 2807 Palma Drive, Ventura, CA 93003, 805-658-1709, www.pacificmarinerepair.com

Salt-Away Products, 1533 E. McFadden Ave., Suite B, Santa Ana, CA 92705, 888-725-8292, www.saltawayproducts.com

Volvo Penta, 1300 Volvo Penta Drive, Chesapeake, VA 23320-9860, 757-436-2800, www.volvo.com/volvopenta